Micro electrical-mechanical systems (MEMS) are typically made from components of 1 to 100 micrometers in size, and MEMS devices generally range in size from 20 micrometers to a millimeter, involving the integration of both electrical and mechanical elements, sensors, actuators, and the like on a substrate utilizing micro-fabrication technology. MEMS devices are particularly useful because they may combine the computational ability of microelectronics with the perception capabilities of microsensors and the precise control capabilities of microactuators. Indeed, the fabrication and integration of these elements on a single substrate may allow the realization of complete systems on a single chip.
MEMS technology has already become commonplace in today's world and is employed in a variety of applications, such as accelerometers that detect collisions in cars, pressure sensors that detect air pressure in car tires, and optical switching for communications. Components of MEMS devices, such as controllers and actuators, often require a power source. In some cases, it may not be desirable, convenient, or feasible to draw power from an external source. As such, battery cells sized for integration in MEMS devices have been developed.
For example, U.S. Pat. Pub. 2004/0191626 to Lewis, Jr. et al. discloses a volumetric lithium-ion battery for use in MEMS. The battery is constructed from materials capable of providing one Joule per cubic millimeter and has a higher capacity than typical planar MEMS batteries because it is thicker in the dimension perpendicular to the plane of the electrodes, designated the Z dimension. The MEMS battery has a volume of approximately one cubic millimeter, and the layers thereof are arranged in a vertically stacked arrangement.
U.S. Pat. No. 5,338,625 to Bates et al. discloses a thin film battery for use in MEMS devices. The battery includes a lithium anode, a vanadium oxide cathode, and an electrochemically stable electrolyte sandwiched therebetween so that the layers are arranged in a vertically stacked arrangement. In order for an implementation of either of these batteries to generate larger voltages, however, it may require many cells arrayed on a large percentage of the available space of the substrate upon which they are carried, which may not be desirable.
U.S. Pat. No. 6,610,440 to LaFollette et al. discloses a battery for use in MEMS. Individual battery cells of this battery each include an anode, a cathode, and an electrolyte sandwiched therebetween so that these layers are arranged in a vertically stacked arrangement. The individual battery cells are arranged adjacent each other on a silicon substrate and may be coupled in series or parallel. The generation of higher voltages with such a battery may require numerous such battery cells, which, in the aggregate, may undesirably consume a large percentage of the available space on the silicon substrate.